The present disclosure generally relates to appliances, and more particularly to a control system for a cooking oven.
In an oven, such as an oven for residential use, the air and surfaces in the cooking chamber (often referred to as the oven cavity) are heated by one or more heat sources, typically two, one on at the top of the oven cavity and the other at the bottom. The food in the oven cavity is cooked by a combination of the heated air (natural convection) and infrared (IR) radiation from the heat sources and the cavity's interior surfaces. The evenness of cooking is a desirable feature for a cooking oven. Some ovens monitor the temperature of the air inside the oven cavity and cycle the heat source on and off to attempt to regulate the temperature of the air. When the heat source is turned on, a considerable amount of energy is used to heat the oven cavity in a relatively short time. This can cause imprecise oven temperature control in the form of temperature overshoot, for example. The temperature overshoot can easily result in temperature variations of approximately 20 degrees Fahrenheit, for example, which can lead to uneven cooking. Also, when the heat source is turned on, a considerable amount of direct infrared (IR) radiation radiates from the heat source and impinges on the surfaces of the food being cooked. For even cooking, without over-browning of the food surfaces, it is often more desirable to have a lower, steady amount of radiation rather than larger, pulsing (bursts of) radiation.
A typical oven will include one or more heating elements, such as a broil heating element at the top of oven and a bake heating element at the bottom of the oven. These heating elements are controlled to regulate the temperature of the oven cavity based on feedback from a temperature sensor located within the oven cavity. However, the combined power requirements of both heating elements, which can easily exceed approximately 30-amperes, can exceed the power delivery capacity of the residential power supply, which is typically around 20-amperes. To prevent the oven from drawing more power than can be supplied, in the typical relay-controlled oven, when cycling the heating elements at a very slow rate, such as in a “bang-bang” or hysteresis type control system or a PI/PID control system, the control system algorithm must prevent both heating elements from being operated at the same time. However, in certain cooking modes, it could be advantageous to provide heat from both the broil and bake heating elements at the same time. While certain oven control systems may control both of the heating elements, these systems typically rely on a varying power ratio between the elements in order to maintain the oven cavity temperature nearly constant. However, a varying power ratio can have an adverse effect on cooking performance.
Accordingly, it would be desirable to provide a control system for an oven that addresses at least some of the problems identified above.